Moonlight synchronous flights across three western palearctic swifts mirror size dependent prey preferences

Abstract

Recent studies have suggested the presence of moonlight mediated behaviour in avian aerial insectivores, such as swifts. At the same time swift species also show differences in prey (size) preferences. Here, we use the combined analysis of state-of-the-art activity logger data across three swift species, the Common, Pallid and Alpine swifts, to quantify flight height and activity responses to crepuscular and nocturnal light conditions. Our results show a significant response in flight heights to moonlight illuminance for Common and Pallid swifts, while a moonlight driven response is absent in Alpine swifts. Swift flight responses followed the size dependent altitude gradient of their insect prey. We show a weak relationship between night-time illuminance driven responses and twilight ascending behaviour, suggesting a decoupling of both crepuscular and night-time behaviour. We suggest that swifts optimise their flight behaviour to adapt to favourable night-time light conditions, driven by light responsive and size-dependent vertical insect stratification and weather conditions.

You are required to cite both the Zenodo data repository as well as the BioRXiv pre-print when using this data, as:

Hufkens et al. 2023. Moonlight synchronous flights across three western palearctic swifts mirror size dependent prey preferences. doi://10.5281/zenodo.7814214

Hufkens et al. 2023. Moonlight synchronous flights across three western palearctic swifts mirror size dependent prey preferences. bioRxiv 2023.04.25.538243; doi: https://doi.org/10.1101/2023.04.25.538243

Use

This is a deposited version of the releases on Github.

Either download this Zenodo repository or clone or download the project Github zip file.

git clone https://github.com/bluegreen-labs/swift_lunar_synchrony.git

Unzip the downloaded data if required. The repository is an `R` project and can be opened in RStudio, which will set the correct relative path.

Data structure & analysis

Analysis data is saved as compressed R serial files (.rds) in the `data` folder. Scripts to reproduce the main statistical results are provided in the `analysis` folder. A matching render of the analysis using the shared data is provided as dynamic webpage.

Licensing

Be mindful of the CC-BY 4.0 license of the data and figures. Reuse is permitted on the condition of proper attribution and documentation of any changes.